If you need a place to store your keys, cash, nano, personal ID and whatever else you carry with you when exercising, a wrist pocket is the way to go. Wrist pockets are discreet, accessible and comfortable. The ones I've posted here are the best I’ve found in terms of design and functionality.
The Amphipod Reflective Wrist Pocket (left side, $15) is my favorite because it stays dry during workouts. It’s adjustable to fit a variety of wrist sizes and has reflective highlights for nighttime safety.
The Craft Pro Cool Wristband (right side, $25) is definitely the most stylish wrist pocket I’ve seen. It comes in bright colors and feels soft and comfortable on your arm. The pocket on this wristband is expandable with mesh ventilation. My only issue with it is that it doesn’t stay as dry as the one Amphipod makes. I recommend it for lower intensity workouts
UPDATE: I recently discovered the Adidas Running Wrist Pocket which has a reflective logo and a simple, sleek design. It's definitely a good one to consider since it carries more than the 2 above.